Water-soluble ammonium or amine salts of phosphate esters of styrene-maleic anhydride copolymer - polyalkylene glycol esters



United States Patent WATER-SOLUBLE AMMONIUM OR AMINE SALTS 0F PHOSPHATE ESTERS 0F STY'RENE-MALEIC ANHYDRIDE COPOLYMER POLYALKYLENE GLYCOL ESTERS Howard D. Gower, Munster, Ind., and Bob G. Gower,

Park Forest, and David W. Young, Homewood, 11]., assignors to Atlantic Richfield Company, a corporation of Pennsylvania No Drawing. Filed July 17, 1968, Ser. No. 745,396

Int. Cl. C1011! 1/44, /24 US. Cl. 26029.6 13 Claims ABSTRACT OF THE DISCLOSURE Water-soluble ammonium or amine salts of phosphate esters of styrene-maleic anhydride copolymer-polyalkylene glycol esters are prepared and can be used when in aqueous solution as metal-working lubricants.

This invention relates to phosphate esters of styrenemaleic anhydride copolymer esters of polyalkylene glycols, to water-soluble ammonium and amine salts thereof, and to aqueous solutions of such salts which have been found to be especially suitable for use as coolants and lubricants in the working of metals.

Lubricants suitable for use in metal fabrication such as cutting, threading, tapping and the like must effectively cool and lubricate both the tool and the worked metal. During such operations an enormous amount of heat is generated at the interface of the tool and the metal being worked which heat must be quickly dissipated in order to prevent damage to either the tool or work piece or both. This is accomplished by flooding the interface with a fluid having a high capacity for heat adsorption as well as effective lubricating properties for reducing friction between the tool and work piece.

The lubricants especially formulated for these purposes are known in the art as cutting fluids or cutting oils. Many of the so-called soluble oils, which are widely used as coolants in metal-working operations, are aqueous emulsions of mineral oils in Water. These compositions may also contain special ingredients which improve, for example, the lubricity, extreme pressure characteristics and corrosion and rust resistant properties of the coolant.

One of the problems associated with these lubricating compositions is their adverse effect on the skin of the machine operators. The mineral oil constituents of these compositions, under the conditions of operation, tend to oxidize rather easily, introducing ingredients which are irritating to the skin and which frequently cause severe allergic reactions. Disintegration of the compounds further leads to the deposition of insoluble materials which accumulate in the pump lines ordinarily used for circulating the coolant, resulting in many cases in undesirable insolubles build-up. Soluble oil coolants based upon mineral oil constituents also tend to form objectionable odors and may present pollution problems upon disposal.

It is therefore an object of this invention to provide an aqueous metal-working coolant and lubricant which is an aqueous solution rather than a mineral oil emulsion. These and other objects are accomplished in accordance with this invention by providing water-soluble amine or ammonium salts of phosphate esters of styrene-maleic anhydride copolymer-polyalkylene glycol esters. The lubricating composition of this invention is an aqueous solution comprising water and the amine or ammonium salts of the phosphate esters of the styrene-maleic anhydride copolymer-polyalkylene glycol ester.

The phosphate esters of this invention can be prepared by first reacting, for instance, a styrene-maleic anhydride copolymer with suitable esterifying agents which provide hydroxy-containing ester groups having a molecular weight of about to 6000, preferably about to 1000. These agents can be, for example, alkylene oxides of about 2 or 3 carbon atoms, i.e. ethylene oxide, propylene oxide and water-soluble polyalkylene glycols. Suitable polyalkylene glycols include the polyethylene glycols and polypropylene glycols of about 100 to 6000, preferably about 150 to 1000 molecular weight. Minor amounts of monofunctional water-soluble alcohols may be present in the esterifying agents, e.g. monohydroxy alcohols of up to 6 carbon atoms or the alkyl-capped polyalkylene glycols, for instance, the methoxy polyethylene glycols of about 300 to 1000 molecular weight. The resulting hydroxy-containing ester is then reacted with phosphoric acid as such or a source of phosphoric acid, e.g. phosphorus pentoxide or polyphosphoric acid.

In preparing the acid form of the salts of this invention the reactants are combined in the mole ratio of about 0.25 to 1 mole of polyalkylene glycol and about 0.5 to 1 mole of phosphoric acid per mole of maleic anhydride in the copolymer. Any tendency to form a polymer ester from the copolymer and the polyalkylene glycol can be reduced by using copolymers whose functionality or free maleic anhydride groups do not materially exceed about 2.5 per copolymer molecule. This can be accomplished by using copolymers whose molecular weight does not exceed about 1000 or in partially pre-esterifying copolymers of higher molecular Weight with a monofunctional, water-soluble alcohol, for instance, of the type noted above.

An acid form of the salts of this invention made from a copolymer having a 1:1 mole ratio of styrene to maleic anhydride, and a polyethylene glycol can be represented by the structure:

wherein x and y are integers and one or both of R and R can be hydrogen or an ester group of the polyethylene glycol or an ester group of the polyethylene glycol ester of the styrene-maleic anhydride copolymer. Also, the copolymer could be partially pre-esterifled, or partially esterified when reacted with the polyalkylene glycol, with a minor amount of mono-functional alcohol as noted above, providing the acid form of the salts of this invention have sufiicient salt-forming sites to give a watersoluble ammonium or amine salt. Both of the reactions, i.e., that between the copolymer and the polyalkylene glycol and that involving the resulting ester and the phosphoric acid component can be conducted at about 50 to C. in the absence of a catalyst. Also, if desired these reactions can be conducted simultaneously.

The styrene-maleic anhydride copolymer resin used in this invention has a molecular weight of about 400 to 5000, preferably about 500 to 2500, and a molar ratio of styrene to maleic anhydride of about 1:1 to 4:1, preferablyabout 1 to 2: 1. Preparation of the styrene-maleic anhydride copolymer can be by known methods. One method is by solution polymerization where the monomers are polymerized in a suitable solvent employing as a polymerization catalyst a free-radical catalyst, huch as a peroxide, preferably benzoyl peroxide, dicumyl peroxide or an alkyl peroxy dicarbonate, at a temperature of about 75 to 300 C. or more. Suitable solvents include the aromatic hydrocarbon solvents, such as cumene, p-cymene, xylene, toluene, etc. Other suitable solvents are the ketones, such as methylethylketone. The preferred manner of carrying out the polymerization is by what is known as incremental feed addition. By this method the monomers and catalyst are first dissolved in a portion of the solvent in which the polymerization is to be conducted and the re sulting solution fed in increments into a reactor containing solvent heated to reaction temperature, usually the reflux temperature of the mixture.

When an aromatic solvent is employed as the solvent for the polymerization, the formation of the copolymer causes a heterogeneous system, the polymer layer being the heavier layer and recoverable by merely decanting the upper aromatic solvent layer and drying. On the other hand, when a ketone is the solvent, the formed copolymer is usually soluble in the solvent media so that recovery of the product necessitates a solvent-stripping operation.

Aqueous solutions of the various water-soluble ammonium salts or water-soluble, salt-forming amines can be employed at ambient temperatures in the present invention to form the salts of the phosphate esters of the styrene-maleic anhydride copolymers. Enough ammonium ion or amine is employed to provide a water-soluble salt and generally these reactants are used in amounts of at least about 0.5 mole per free catalyst group of the copolymer-polyalkylene glycol-phosphoric acid reaction product. Preferably the salt is essentially neutral due to the use of a sufiicient amount of the ammonium ion or amine. Preferred water-soluble, salt-forming amines have boiling points above about 200 C. These preferred amines include the tertiary amines such as, for example, trifurfurylamines, and hydroxyl alkyl amines of at least 2 carbon atoms in the alkyl groups such as, for example, triethanolamine. Glycol amines of molecular weight up to about 1500 or capped glycol amines of molecular weights up to about 5000 are also suitable.

The metal-working fluids of the present invention are usually prepared as aqueous solution concentrates containing a minor proportion of the amine or ammonium salts.

Often these solutions are about 5 to 50 weight percent concentrates which during use in working metals are diluted with greater volumes of Water, e.g. about 5 to 200 or more volumes.

Example I describes a typical procedure for the preparation of the phosphate esters of this invention.

EXAMPLE I To a 1 liter resin kettel were added 303 g. of a copolymer of styrene and maleic anhydride having a styrene to maleic anhydride mole ratio of 1:1 and an average molecular weight of about 600, and 450 g. of polyethylene glycol of molecular weight of about 300. The mixture was purged thoroughly with nitrogen, heated to 150 C. and maintained at this temperature with stirring for 1 hour. The ester product was a light yellow, viscous liquid. Three hundred grams of this reaction product and 102 grams of polyphosphoric acid (H P -O molecular weight of 338) were heated at 7080 C. for 30 minutes. The resulting phosphoric acid ester of the styrene-maleic anhydride copolymer-polyethylene glycol ester was then dissolved in sufilcient Water to form a weight percent Table I Composition A Steel 487 Copper 415 Aluminum 392 From the data in Table I it is apparent that use of aqueous fluids containing the styrene-maleic anhydride copolymer phosphate ester salts of this invention results in lower torque values.

It is claimed:

1. The phosphoric acid esters of styrene-maleic anhydride copolymer esters of polyalkylene glycols, said phosphate esters being of a styrene-maleic anhydride copolymer having a molecular weight of about 400 to 5000 and a molar ratio of styrene to maleic anhydride of about 1:1 to 4:1 and a polyalkylene glycol having alkylene groups of 2 to 3 carbon atoms and a molecular Weight of about to 6000, said phosphoric acid esters having a mole ratio of polyalkylene glycol to phosphoric acid to maleic anhydride of said styrene maleic anhydride copolymer of about 0.25 to 1:about 0.5 to 1:about 1.

2. The phosphate ester of claim 1 wherein the molecular weight of said styrene-maleic anhydride copolymer is about 500 to 2500 and the molar ratio of styrene to maleic anhydride is about 1 to 2:1 and the molecular weight of said polyalkylene glycol is about to 1000.

3. The phosphate ester of claim 2 wherein said polyalkylene glycol is polyethylene glycol.

4. The water-soluble salts of the phosphate ester of claim 1 and a member selected from the group consisting of ammonium ion and water-soluble, salt-forming amines.

5. The water-soluble salts of the phosphate ester of claim 3 and a member selected from the group consisting of ammonium ion and water-soluble, salt-forming amines.

6. The composition of claim 4 wherein said salt-forming amine has a boiling point above about 200 C.

7. The composition of claim 6 wherein said salt-forming amine is triethanolamine.

8. The composition of claim 5 wherein said salt-forming amine is triethanolamine.

9. An aqueous solution containing about 5 to 50 weight percent of the composition of claim 4.

10. An aqueous solution containing about 5 to 50 weight percent of the composition of claim 5.

11. An aqueous solution containing about 5 to 50 weight percent of the composition of claim 6.

12. An aqueous solution containing about 5 to 50 weight percent of the composition of claim 7.

13. An aqueous solution containing about 5 to 50 Weight percent of the composition of claim 8.

References Cited UNITED STATES PATENTS 3,085,986 4/1963 Muskat. 3,245,933 4/1966 Muskat.

JULIUS FROME, Primary Examiner J. B. LOWE, Assistant Examiner US. Cl. X.R. 

